version: '3.8'

# Shared Redis Cache
# Purpose: Centralized cache and session store for all homelab applications
# Port: 6379
# GPU: No
# Storage: SSD (Redis persistence - AOF and RDB)

services:
  redis-shared:
    image: redis:alpine
    container_name: redis-shared
    restart: unless-stopped
    command: >
      redis-server
      --appendonly yes
      --appendfsync everysec
      --maxmemory 512mb
      --maxmemory-policy allkeys-lru
      --save 60 1000
      --save 300 100
      --save 900 1
      --loglevel warning
    healthcheck:
      test: ["CMD-SHELL", "redis-cli ping | grep PONG"]
      start_period: 20s
      interval: 30s
      retries: 5
      timeout: 3s
    ports:
      - "6379:6379"
    volumes:
      - /home/jpmschweitzer/docker-data/redis-shared/data:/data
    environment:
      TZ: Europe/Amsterdam
    deploy:
      resources:
        limits:
          cpus: '0.5'
          memory: 512M
        reservations:
          memory: 128M
    networks:
      - docker-dataplane

networks:
  docker-dataplane:
    external: true
    name: docker-dataplane

# Setup Instructions:
#
# 1. Create directories:
#    mkdir -p ~/docker-data/redis-shared/data
#
# 2. Deploy stack:
#    docker-compose -f redis-shared.yml up -d
#
# 3. Verify deployment:
#    docker exec redis-shared redis-cli ping
#
# Database Allocation:
#
# Redis supports 16 databases (0-15). Assign one per application:
#
#   DB 0: Authentik (sessions, cache, message queue)
#   DB 1: Tatlock (memory)
#   DB 2: Wiki.js
#   DB 3: Scheduler
#   DB 4: Library Desk
#   DB 5: SearXNG
#   DB 6: Tatlock (benchmarks)
#   DB 7: Nextcloud (file locking, distributed cache, sessions)
#   DB 8: Paperless (task queue, cache)
#   DB 9-15: Reserved for future applications
#
# Connection Examples:
#
# From containers on docker-dataplane network:
#   redis://redis-shared:6379/1  (Authentik, DB 1)
#   redis://redis-shared:6379/2  (Gitea, DB 2)
#
# From host machine:
#   redis-cli -h localhost
#   SELECT 1  (switch to database 1)
#
# Monitoring:
#
# General info:
#   docker exec redis-shared redis-cli INFO
#
# Memory usage:
#   docker exec redis-shared redis-cli INFO memory
#
# Keyspace (keys per database):
#   docker exec redis-shared redis-cli INFO keyspace
#
# Stats:
#   docker exec redis-shared redis-cli INFO stats
#
# Per-database keys:
#   docker exec redis-shared redis-cli -n 1 DBSIZE  (database 1)
#   docker exec redis-shared redis-cli -n 2 DBSIZE  (database 2)
#
# Backup:
#
# Trigger background save:
#   docker exec redis-shared redis-cli BGSAVE
#
# Copy RDB file:
#   cp ~/docker-data/redis-shared/data/dump.rdb \
#      ~/backups/redis-$(date +%Y%m%d).rdb
#
# Backup AOF (append-only file):
#   cp ~/docker-data/redis-shared/data/appendonly.aof \
#      ~/backups/redis-aof-$(date +%Y%m%d).aof
#
# Restore:
#   docker stop redis-shared
#   cp backup-dump.rdb ~/docker-data/redis-shared/data/dump.rdb
#   docker start redis-shared
#
# Maintenance:
#
# Clear specific database (DANGER - data loss!):
#   docker exec redis-shared redis-cli -n 1 FLUSHDB
#
# Clear all databases (DANGER - total data loss!):
#   docker exec redis-shared redis-cli FLUSHALL
#
# Rewrite AOF (compact log file):
#   docker exec redis-shared redis-cli BGREWRITEAOF
#
# Configuration Details:
#
# Persistence strategy (dual):
#   - AOF (Append Only File): Real-time durability, fsync every second
#   - RDB Snapshots: Periodic snapshots (every 60s if 1000+ keys changed)
#
# Memory policy:
#   - Max memory: 512MB
#   - Eviction: allkeys-lru (Least Recently Used eviction when full)
#
# Resource Usage (expected):
#   CPU: ~0.1-0.3 cores (low CPU, very efficient)
#   RAM: ~100-400MB (depends on data, capped at 512MB)
#   Storage: ~50-200MB (AOF + RDB files)
#
# Applications Using This Cache:
#   - Authentik (sessions, policies, background tasks)
#   - Gitea (sessions, cache, queues) - if migrated
#   - Nextcloud (file locking, distributed cache, sessions)
#   - Future applications as needed
#
# Performance Tips:
#   - Use pipeline commands for bulk operations
#   - Set appropriate TTL (Time To Live) on cached keys
#   - Monitor memory usage to prevent eviction storms
#   - Use database numbers to isolate application data